Occasionally slowing down your pace can actually make you run faster in the long-term. That means running at a pace that doesn’t tax your body. The most common mistake most runners make is that they think if they’re running easily then they’re not getting much benefit but that couldn’t be more off-base because easy running comes with considerable benefits.
First of all, as your body becomes more adapted to aerobic, slow runs, it’s going to use fat more efficiently. This process is known as the fat adaptation effect. Faster anaerobic runs mainly deplete stored muscle glycogen from carbohydrates. Slower aerobic runs use approximately 80 percent fat for energy while the remaining 20 percent is a combination of glucose and protein. The reason for this? Fat oxidation requires oxygen—and it’s very hard to run long distances at an all-out fast pace. Long, slow distance runs are easier to sustain. So during these runs, your body has to constantly replenish the oxygen reserves it’s using to continue to produce energy. And since fat metabolism requires oxygen, you condition your body to use fat as its main energy source rather than carbs. Eventually, this adaptation will allow you to run longer distances without having to refuel.
Easy runs also train the cardio, respiratory, and muscular systems to work more efficiently. They allow the body to better integrate its various systems. In turn, this will allow you to run with less effort on your faster running days. Slower runs also train your slow twitch (type I) muscle fibers, the ones that allow you to work aerobically to sustain your pace on long distances. And while faster running is more likely to build up your muscle, slower running is going to help your tendons, ligaments, joints, and bones adapt to the stress of running. It also strengthens them without causing immediate stress on them, which might lead to injury. The extra bonus there? That’s going to promote efficient running form because slower runs make it easier to focus on technique. During faster runs the blood circulates away from your brain to meet the body’s oxygen demands, decreasing your ability to focus. So slowing down can help you zoom in on running
How Often Should You Be Running Slower? This might come as a surprise, but most of your runs should be slow. Running too fast too often can actually backfire. You won’t develop the fast twitch (type II) muscle fibers necessary to withstand a long race. Fast twitch muscle fibers are extremely important for your last ‘kick’ in a race. Without an adequate supply of fast twitch muscle fibers, you simply won’t have the strength to run at your maximal pace at the end. You also won’t rest and recover as well, you’ll go into your next speed or technique workout and your risk of injury goes up—you might suffer some setbacks, and then you’re not as consistent, and you’re not improving as much long-term. So the subtle things can make a big difference.
As much as you might want to bang out those shorter, easier runs just to get them done, you can’t run hard all the time. To stay healthy long-term, it’s about giving every run a purpose—and sometimes that means taking it slow.